diff --git a/codelabs/custom_toolbox/custom_toolbox.md b/codelabs/custom_toolbox/custom_toolbox.md
index e8392bdf2..2723b7707 100644
--- a/codelabs/custom_toolbox/custom_toolbox.md
+++ b/codelabs/custom_toolbox/custom_toolbox.md
@@ -174,7 +174,7 @@ Copy and paste the following CSS into your `toolbox_style.css` file.
   color: white;
 }
 /* Adds padding around the group of categories and separators. */
-.blocklyToolboxContents {
+.blocklyToolboxCategoryGroup {
   padding: 0.5em;
 }
 /* Adds space between the categories, rounds the corners and adds space around the label. */
diff --git a/examples/custom-toolbox-codelab/complete-code/toolbox_style.css b/examples/custom-toolbox-codelab/complete-code/toolbox_style.css
index 2bbf7090b..067e90aba 100644
--- a/examples/custom-toolbox-codelab/complete-code/toolbox_style.css
+++ b/examples/custom-toolbox-codelab/complete-code/toolbox_style.css
@@ -3,7 +3,7 @@
   color: #fff;
 }
 /* Adds padding around the group of categories and separators. */
-.blocklyToolboxContents {
+.blocklyToolboxCategoryGroup {
   padding: 0.5em;
 }
 /* Adds space between the categories, rounds the corners and adds space around the label. */